In an excavator as a construction machine, various kinds of components required to operate the machine, for example, components including a turning joint or a swing drive, and a main control valve or a hydraulic valve are equipped inside an upper swing structure between a rear portion of a boom base and an engine room. The scratch work of the excavator requires advanced professional capability to manipulate the work apparatus or the machine since rocks or stones should be crushed, collected or loaded through a boom-bucket manipulation on a construction side including a rocky mountain or a hill.
FIG. 1 is a diagrammatic view schematically showing an example in which a scratch work is performed through a conventional excavator in accordance with the prior art.
In general, an excavator is provided with a lower traveling structure 1 including a track, and an upper swing structure 2 including a bucket 3, an arm 4, a boom 5, an operator's cab 6, a fuel tank 7, a hydraulic tank 8, and a cowl frame 9, which are equipped on the lower traveling structure 1. All the components included in the upper swing structure 2 can typically be equipped on an upper frame.
Distal ends of the boom 5 and the arm 4 supporting the bucket 3 maintain an erected posture at a position higher than that of the operator's cab 6 of the upper swing structure 2, and the bucket 3 crushes or scratches rocks or stones included in a rocky mountain through the operator's manipulation and during a scratch work of the excavator.
In this case, there frequently occurs a phenomenon in which foreign substances R including pieces of rocks and stones fall into the upper swing structure 2 in the rear of the boom 5.
For example, as shown in FIG. 2, a rear portion of a boom base provided at a lower portion of the boom 5 is generally positioned in the proximity of the top center portion of the upper swing structure 2, and a separate protection structure is not designed to be disposed adjacent to the fuel tank 7 or the hydraulic tank 8 and the cowl frame 9. For this reason, the foreign substances directly fall into the upper swing structure 2 in terms of the structure of the boom base.
Therefore, such a conventional excavator entails a problem in that the foreign substances R including pieces of rocks and stones fall in the rear of the boom or the boom base during a scratch work of the excavator, thereby causing a damage to the components including hydraulic valve and the turning joint that are equipped inside the upper swing structure